1. Field of the Invention
The present invention relates to a equipment for fabricating a semiconductor device, and more particularly to a cluster tool having a wafer cooling apparatus for fabricating a semiconductor device that is capable of solving a problem of bottleneck occurring in performing processes for fabricating a semiconductor device.
2. Description of the Background Art
A cluster tool for fabricating a semiconductor device refers to a multiple reaction chamber type composite equipment which includes a polyhedral transfer chamber with a wafer handling robot inserted at the center thereof, a plurality of process chambers positioned at each wall face of the polyhedral transfer chamber; and a loadlock chamber installed at a different wall face of the transfer chamber.
FIG. 1 is a schematic view illustrating a construction of the cluster tool 100 for fabricating a semiconductor device. At the center of the cluster tool, there is installed a wafer transfer chamber 130. The transfer chamber 130 is formed in a polyprism shape having a plurality of wall faces, and a wafer handling robot 132 is installed at the central portion of the transfer chamber 130 to transfer automatically the Wafer 140.
The wafer transfer robot 132 takes out the wafer 140 from the process chambers 110a, 110b and 110c and transfers it to loadlock chambers 120a and 120b or transfers the wafer from the loadlock chambers 120a and 120b to the process chambers 110a, 110b and 110c. 
The plurality of process chambers 110a, 110b and 110c are attached at the plurality of wall faces of the transfer chamber 130, respectively.
A wafer aligner 122 and a first loadlock chamber 120a are attached in serial at a wall face of the transfer chamber 130. A cooling plate 124 and a second loadlock chamber 120b are installed at a wall face of the transfer chamber 130. The first and the second loadlock chambers 120a and 120b include a cassette (not shown) respectively with a plurality of wafers mounted thereon.
The operation of the cluster tool for fabricating a semiconductor device constructed as described above will now be explained.
First, a cassette (not shown) having the plurality of wafers is mounted at the first loadlock chamber 120a. 
Next, the pressure in the first loadlock chamber 120a is lowered to a certain level by means of a vacuum pump.
When the pressure of the first loadlock chamber 120a is lowered to a desired level, the wafer handling robot 132 takes out the wafer from the cassette and puts it on the wafer aligner 122 for flat zone alignment of the wafer.
The aligned wafer is put into the process chamber 110a by the wafer handling robot 132 and undergoes fabrication processes of a semiconductor device.
In case that a unit process in fabricating a semiconductor device is performed in a state that the wafer is heated, after the process is completed, the wafer is taken out from the process chamber 110a by the wafer handling robot 132 and mounted on the cooling plate 124, that is, an incooler, so as to be cooled at a room temperature.
The cooled wafer is put in the cassette of the second loadlock chamber 120b by the wafer handling robot 132 and then fetched out from the cluster tool.
In case that the temperature in the process chamber 110a, 110b, 110c is more than 300xc2x0 C., approximately, it takes 100 seconds to cool the wafer on the cooling plate 124 of the cooling chamber 130.
In this respect, however, the cooling plate 124 of the cluster tool for fabricating a semiconductor device of the conventional art allows only one wafer to be mounted. Thus, when the plurality of process chambers performs the processes simultaneously at a high temperature, a process bottle neck phenomenon occurs due to the delay in cooling of the wafer.
In other words, even though the fabrication process of a semiconductor device is terminated in each process chamber, since the wafer is mounted on the cooling plate only one by one, in case that other wafer is in the state of cooling, the process is in a standby state without proceeding further process successively, causing a problem that the overall term of the fabrication process of a semiconductor device is lengthened.
Therefore, an object of the present invention is to provide a cluster tool for fabricating a semiconductor device that is capable of removing the process bottle neck phenomenon caused due to delay in cooling a wafer of a cluster tool having a plurality of process chamber.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a cluster tool for fabricating a semiconductor device comprising: a transfer chamber having a wafer handling robot in center portion and a plurality of wall faces; a plurality of process chambers installed adjacent to each wall face of the transfer chamber; a loadlock chamber installed adjacent to a wall face of the transfer chamber, in which a cassette is positioned to bring in and take out a wafer; and a cooling chamber installed at a wall face of the transfer chamber with an open-and-shut unit therebetween, the cooling chamber being provided with a wafer multiple-mounting unit having a plurality of wafer mounting plates for simultaneously mounting wafers which finishes undergoing processes in the process chamber and cooling them.
In the cluster tool for fabricating a semiconductor device of the present invention, a wafer contact portion of the wafer mounting plate is made of ceramic or quartz.
In the cluster tool for fabricating a semiconductor device of the present invention, the wafer mounting plate includes a stainless steel plate and a ceramic layer or a quartz layer coated at the upper portion of the stainless steel plate.
In the cluster tool for fabricating a semiconductor device of the present invention, the number of the wafer mounting plates are five or 25.
In the cluster tool for fabricating a semiconductor device of the present invention, a cooling gas injection pipe is connected with the cooling chamber to inject a cooling gas of nitrogen or argon in the cooling chamber.
In the cluster tool for fabricating a semiconductor device of the present invention, a water cooled tube is installed to surround the wall of the cooling chamber to cool the inner side of the cooling chamber.
In order to achieve the above objects, the cluster tool for fabricating a semiconductor device further includes: an open-and-shut unit provided at both walls of the loadlock chamber and of the cooling chamber so as for the cooling chamber and the loadlock chamber to selectively communicate with each other; a cassette transfering device for moving the cassette and a wafer multiple-mounting unit transferring device for moving the wafer multiple-mounting unit.
In the cluster tool for fabricating a semiconductor device of the present invention, the cassette transfering device reciprocally rotates the cassette between the transfer chamber direction and the wafer multiple-mounting unit direction, and the wafer multiple-mounting unit moving device includes: a first unit for reciprocally rotating the wafer multiple-mounting unit between the transfer module direction and the cassette direction; a second unit for adjusting a height of the wafer mounting plate to a slot position of the cassette; and a third unit for forwarding the wafer multiple-mounting unit to the cassette and retreating it.
In the cluster tool for fabricating a semiconductor device of the present invention, the second unit is a vertical transfer unit of the wafer multiple-mounting unit itself or a vertical shift unit of the wafer mounting plate itself.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.